Adaptive fuzzy control‐based projective synchronization of uncertain nonaffine chaotic systems

This article aims to introduce a projective synchronization approach based on adaptive fuzzy control for a class of perturbed uncertain multivariable nonaffine chaotic systems. The fuzzy‐logic systems are employed to approximate online the uncertain functions. A Lyapunov approach is used to design the parameter adaptation laws and to demonstrate the boundedness of all signals of the closed‐loop system as well as the convergence of the synchronization errors to bounded residual sets. Finally, numerical simulation results are presented to verify the feasibility and effectiveness of the proposed synchronization system based on fuzzy adaptive controller. © 2014 Wiley Periodicals, Inc. Complexity 21: 180–192, 2015     

Missing boundary data recovering for the Helmholtz problem

This Note is dedicated to the numerical treatment of the ill-posed Cauchy–Helmholtz problem. Resorting to the domain decomposition tools, these missing boundary data are rephrased through an ‘interfacial’ equation. This equation is solved via a preconditioned Richardson algorithm with dynamic relaxation. The efficiency of the proposed method is illustrated by some numerical experiments. To cite this article: R. Ben Fatma et al., C. R. Mecanique 335 (2007).     

N-Octyl Quaternized P4VP Interaction With Orange Telon

The removal of orange Telon from aqueous solutions by poly(N-octyl-4-vinylpyridiniumbromide) copolymer was investigated. Batch adsorption experiments were carried out to study the effect of experimental parameters on the orange Telon adsorption equilibrium. The adsorption characteristics of copolymer to ward orange Telon in dilute aqueous solution were followed using UV-Vis spectrophotometry. Adsorption equilibrium was reached within 60 min for 0.03 g of poly(4-vinylpyridine quaternized at 58%. The kinetic of adsorption is best described by a pseudo-second-order model. Results also showed that the equilibrium modeling of orange Telon removal process was described by Langmuir isotherms. The maximum adsorption capacity determined from the Langmuir isotherm was 76.4 mg g^{? 1}. The study of the thermodynamic parameters showed that the adsorption of orange Telon on copolymer is an exothermic process and the randomness decreases at the solid-solution interface during the adsorption of dye on the copolymer.     

Experimental investigations and modelling studies of ozone producing corona discharges

The ozone generation by negative corona discharge in coaxial cylindrical system of electrodes have been studied experimentally in Ar+O₂ and N₂+O₂ mixtures. Both in argon and nitrogen mixtures with oxygen the monotonous decrease in ozone concentration [O₃] was observed at decreasing oxygen content in mixtures and the constant input energy density η. The rate coefficients for the ozone generation and ozone decomposition were obtained by fitting experimentally measured data [O₃]=f(η) with Vasiljev-Eremin formula. The calculated rate coefficient for ozone generation in N₂+O₂ mixtures at low content of oxygen (below 20%) was found considerably higher than that in Ar+O₂ mixtures. Increase in the rate coefficients for ozone generation and decomposition was observed with decreasing content of oxygen in both mixtures. The experimental results are in qualitative agreement with the simple model incorporating five main chemical processes in mechanism of ozone generation. The research was partially supported by Slovak Grant Agency under project 1/765920 The UK EPSRC (Grant GM/98944) and NATO Joint Project PST CLG 976544.     

On the limit cycles for a class of generalized Kukles differential systems

In this paper, we consider the limit cycles of a class of polynomial differential systems of the form $\dot{x}=-y, \hspace{0.2cm} \dot{y}=x-f(x)-g(x)y-h(x)y^{2}-l(x)y^{3},$ where $f(x)=\epsilon f_{1}(x)+\epsilon^{2}f_{2}(x),$ $g(x)=\epsilon g_{1}(x)+\epsilon^{2}g_{2}(x),$ $h(x)=\epsilon h_{1}(x)+\epsilon^{2}h_{2}(x)$ and $l(x)=\epsilon l_{1}(x)+\epsilon^{2}l_{2}(x)$ where $f_{k}(x),$ $g_{k}(x),$ $h_{k}(x)$ and $l_{k}(x)$ have degree $n_{1},$ $n_{2},$ $n_{3}$ and $n_{4},$ respectively for each $k=1,2,$ and $\varepsilon$ is a small parameter. We obtain the maximum number of limit cycles that bifurcate from the periodic orbits of the linear center $\dot{x}=-y,$ $\dot{y}=x$ using the averaging theory of first and second order.     

An Aitken-like acceleration method applied to missing boundary data reconstruction for the Cauchy–Helmholtz problem

This Note is concerned with the severely ill-posed Cauchy–Helmholtz problem. This Cauchy problem being rephrased through an “interfacial” equation, we resort to an Aitken–Schwarz method for solving this equation. Numerical trials highlight the efficiency of the present method.     

Thermal stability of atmospheric plasma sprayed (Ni, Cu, Co)–YSZ and Ni–Cu–Co–YSZ anodes cermets for SOFC application

This paper reports the results of the thermal stability study of M–YSZ (M=Ni, Cu, Co, Cu–Co, Ni–Cu–Co) SOFC anode cermets materials at different heat treatment temperatures. The cermets were elaborated by atmospheric plasma spraying (APS) with optimized conditions and then submitted to heat treatments at 800 and 1000 °C, respectively. Scanning electron microscopy and X-ray diffraction were used to characterize, respectively, the morphology and structure of obtained films, before and after thermal annealing. A correlation was made between the differential scanning calorimetry analysis results and those obtained by X-ray diffraction. Focusing, in this study, on YSZ matrix thermal stability, the obtained results were as follows: the monometallic cermets with the lowest amount of metal and the trimetallic one exhibited a good stability at 800 °C, whereas at 1000 °C, all considered cermets were unstable with a eutectoid decomposition of YSZ matrix.     

N,N'-SUBStituted 1,2,5 thiadiazolidine 1,1-dioxides: synthesis, selected chemical and spectral proprieties and antimicrobial evaluation

The sulfamide functional group is increasingly relevant in both medicinal and bioorganic chemistry. We report here practical access to a series of N2,N5-substituted five-membered cyclosulfamides. The five-membered heterocyclic motif was prepared starting from proteogenic amino acids and chlorosulfonyl isocyanate via the Mitsunobu reaction. Selected chemical and spectral proprieties and the antimicrobial evaluation of these compounds are detailed.     

The solvolysis oftrans-[Co(4-Mepy)4Cl2]ClO4 in water-methanol mixtures

Summary The solvolysis of thetrans-[Co(4-Mepy)₄Cl₂]ClO₄ complex was studied in 0 to 70% v/v H₂O: MeOH mixtures at 40, 45, 50 and 55 °C. The high negative S^* values found for the complex cation under investigation, relative to that oftrans- [Co(py)₄Cl₂]⁺ reported in the literature, were attributed to the substituent methyl groups. The free energies of transfer of both the ground and the transition states were calculated from which the dominant effect of the solvent on the transition state is apparent.     

Tetranuclear cobalt trimethylacetate Co4(μ3-OH)2(μ-OOCBut)6(C4H6N2O)4 containing coordinated 3-methyl-5-pyrazolone

We found that the reaction of the compound obtained by alloying hydrous cobalt(II) acetate and pivalic acid with 3-methyl-5-pyrazolone in refluxing hexane produces the tetranuclear complex Co₄(μ₃-OH)₂(μ-OOCBu^t)₆·(C₄H₆N₂O)₄·2HOOCBu^t (complex 3). The complex has been structurally characterized using single-crystal X-ray diffraction